In general, as shown in FIG. 1, an air conditioning system for a vehicle has a refrigeration cycle that includes: a compressor 1 for compressing and discharging refrigerant; a condenser 2 for condensing the refrigerant of high pressure discharged from the compressor 1; an expansion valve 3 for throttling the refrigerant condensed and liquefied in the condenser 2; and an evaporator 4 for exchanging heat between the liquefied refrigerant of low pressure throttled by the expansion valve 3 and air blown to the interior of the vehicle and for evaporating the refrigerant to cool the air discharged to the interior of the vehicle through heat absorption by evaporative latent heat, and that the compressor 1, the condenser 2, the expansion valve 3 and the evaporator 4 are connected with one another via refrigeration pipes. The air conditioning system cools the interior of the vehicle through the following refrigerant circulation process.
When a cooling switch (not shown) of the air conditioning system is turned on, first, the compressor 1 inhales and compresses vapor-phase refrigerant of low-temperature and low-pressure while driving by driving power of an engine or a motor, and then sends the refrigerant in the gaseous phase of high-temperature and high-pressure to the condenser 2. Then, the condenser 2 condenses the vapor-phase refrigerant into liquid-phase refrigerant of high-temperature and high-pressure by exchanging heat with outdoor air. After that, the liquid-phase refrigerant of high-temperature and high-pressure sent from the condenser 2 rapidly expands by a throttling action of the expansion valve 3 and is sent to the evaporator 4 in a wet-saturated state of low-temperature and low-pressure. The evaporator 4 exchanges heat between the refrigerant and air blown to the interior of the vehicle by a blower (not shown). Then, the refrigerant is evaporated in the evaporator 4 and discharged in a gaseous phase of low-temperature and low-pressure. After that, the vapor-phase refrigerant is inhaled into the compressor 1, and then, recirculates the refrigeration cycle as described above. The evaporator is mounted inside the air-conditioning case mounted to the interior of the vehicle to cool the interior of the vehicle. That is, the air blown by the blower (not shown) is cooled by evaporative latent heat of the liquid-phase refrigerant circulating inside the evaporator 4 and discharged to the interior of the vehicle in a cooled state so as to cool the interior of the vehicle. Moreover, the interior of the vehicle is heated by a heater core (not shown), which is mounted inside the air-conditioning case, and, through which coolant of the engine circulates, or by an electric heater (not shown) mounted inside the air-conditioning case. In the meantime, the condenser 2 is mounted at the front side of the vehicle to radiate heat while exchanging heat with air.
Recently, an air conditioning system which carries out heating and cooling only using a refrigeration cycle has been developed. As shown in FIG. 2, such an air conditioning system includes: a cold air passageway 11 and a warm air passageway 12 which are partitioned to the right and the left inside one air-conditioning case 10; an evaporator 4 mounted on the cold air passageway 11 for cooling; and a condenser 2 mounted on the warm air passageway 12 for heating. In this instance, at an outlet of the air-conditioning case 10, formed are a plurality of air outflow ports 15 for supplying air to the interior of the vehicle and a plurality of air discharge ports 16 for discharging air to the exterior of the vehicle.
Furthermore, blowers 20 which are operated individually are respectively mounted at an inlet of the cold air passageway 11 and at an inlet of the warm air passageway 12. The air-conditioning case 10 and the blowers 20 in the air conditioning system are mounted inside the interior of the vehicle based on a dash panel (not shown), which partitions an engine room from the interior of the vehicle. Therefore, in a cooling mode, cold air cooled while passing through the evaporator 4 of the cold air passageway 11 is discharged to the interior of the vehicle through the air outflow port 15 to cool the interior of the vehicle, and in this instance, warm air heated while passing through the condenser 2 of the warm air passageway 12 is discharged to the exterior of the vehicle through the air discharge port 16.
In a heating mode, warm air heated while passing through the condenser 2 of the warm air passageway 12 is discharged to the interior of the vehicle through the air outflow port 15 to heat the interior of the vehicle, and in this instance, cold air cooled while passing through the evaporator 4 of the cold air passageway 11 is discharged to the exterior of the vehicle through the air discharge port 16.
However, the conventional air conditioning system must discharge hot air passing through the condenser to the outside through the air discharge port 16 in the cooling mode and discharge cold air passing through the evaporator to the outside through the air discharge port 16. In the above process, the conventional air conditioning system has several disadvantages in that the outdoor air flows backward through the air discharge port 16 due to wind pressure while the vehicle runs, and in that cooling performance and heating performance are deteriorated because heat is not discharged smoothly through the air discharge port 16.